I read below in other comments that this game is moving to Steam. Is it listed as an upcoming game yet? Do you know when it will be released? Will it be early access at first?
The law says that Steam needs to have a full age registration by uploading an official document like drivers license or something. The Law was there for years but they enforce it more like from 2021 or something and steam either needs to update theire age verification or they just block sexual games in general in Germany.